JP3158940B2 - Lost mud prevention method in muddy water method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing muddy water in a muddy water method, and more particularly to a method for excavating a slot in the ground to construct an underground structure such as an underground continuous wall or a cast-in-place pile. In the muddy water method, which supplies and fills the muddy water into the slot and uses it as a stabilizing liquid to prevent the collapse of the wall of the slot and excavate, the supplied muddy water is prevented from escaping to the ground around the slot. The present invention relates to a method for preventing muddy water in a muddy water method.

[0002]

2. Description of the Related Art A muddy water method used when excavating and forming a slot in the ground is, for example, in a continuous underground wall method or a cast-in-place pile method, a slot for filling a hardened material such as concrete. When excavating using various vertical hole excavators such as a vertical trench excavator for underground diaphragm wall and a reverse circulation drill, to prevent collapse of the trench wall surface during or after excavation, bentonite muddy water, In this method, excavation work is performed while supplying and filling muddy water such as polymer muddy water and self-hardening stabilizing liquid into a slot as a stable liquid.

According to the muddy water method, the wall surface of the slot is pressed with a specific gravity greater than that of the groundwater of the muddy water, and a water-blocking layer is formed on the wall surface of the groove with a clay-like component contained in the muddy water. By these, the wall surface of the slot can be stably held until the hardening material such as concrete is filled into the slot by replacing with muddy water, and the self-hardening stabilizing liquid or the like can harden itself. According to the muddy water that can be formed, the muddy water can be cured as it is to form an underground structure.

[0004] However, while such a muddy water method has technically excellent advantages as described above, when it encounters a ground having a large gap between soil particles such as a gravel ground or a gravel ground during excavation work, The muddy water escapes to the surrounding ground through these gaps, causing problems such as the collapse of the wall of the slot or the need to supply a large amount of muddy water. There was a case.

[0005] As a conventional means for preventing such lost mud, generally, mineral powder, asbestos, pulp, fiber waste and the like are mixed in muddy water, and the gaps in the ground are clogged by these. A method for preventing the escape of muddy water is known.

[0006]

However, according to the method for preventing lost water in the above-mentioned conventional muddy water method, mineral powder, asbestos, pulp, fiber waste and the like can be relatively easily dispersed and mixed into the muddy water. In addition, it is effective for adhering to the surface layer portion of the slot wall surface and clogging the gap in the ground at the surface layer portion. However, since all of these sludge prevention materials have poor permeability into the ground, , It does not spread sufficiently from the groove wall surface to the deep position of the ground through the gap, so that the effect of preventing sludge loss may not be sufficiently exhibited, and the effect of preventing sludge loss is maintained for a long time There was a problem that it was difficult.

Accordingly, the present invention has been made in view of these technical problems, and a sludge preventing material mixed with muddy water to prevent sludge is widely spread on the ground around the slot. It is an object of the present invention to provide a method for preventing muddy water in a muddy water method that can spread the effect of preventing muddy loss and maintain the effect for a long time.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and its gist is to provide an underground structure for constructing an underground structure such as an underground continuous wall or a cast-in-place pile. When excavating a slot, mud is supplied and filled into the slot, and the mud is supplied to the ground as a stabilizing liquid to prevent excavation work while preventing collapse of the wall of the slot. Is a method of preventing muddy water in the muddy water method to prevent the muddy water from escaping into the ground.
If so, the muddy water near the ground in
Feed water-swellable fiber as aqueous fiber with electrolyte
And a method for preventing lost water in a muddy water method characterized by mixing the same.

[0009]

[0010]

[0011]

Hereinafter, the invention according to this application will be described in more detail. The method for preventing muddy water in the muddy water method according to the present invention is characterized in that when excavating a slot in the ground to construct an underground structure such as an underground continuous wall or a cast-in-place pile, muddy water is supplied and filled into the slot. In the muddy water method that uses this as a stabilizing liquid to prevent excavation work while preventing collapse of the slot wall surface, a method for preventing lost muddy water in the muddy water method to prevent the supplied muddy water from escaping to the ground around the groove And produce sludge such as a gravel layer
If you encounter easy-to-use ground,
Water swellable fiber as superabsorbent fiber in muddy water
Both are fed and mixed.

That is, the present invention relates to a method of excavating and forming a slot in the ground while using the mud as a stabilizing liquid, which is conventionally known as a muddy method. It has been adopted to prevent escape to the surrounding ground when encountering.

According to the method for preventing lost water according to the present invention, the highly water-absorbing fiber is mixed into the muddy water supplied during or after excavation as a material for preventing lost water.

Here, the mud in the above description includes:
Various types of conventionally known muddy water can be used as the muddy water used in the muddy water method.Specifically, for example, in addition to bentonite muddy water, polymer muddy water, etc., blast furnace cement, bentonite, etc., and self-hardening muddy water are used. Certain self-hardening stabilizers and the like can also be used.

The superabsorbent fiber mixed into the muddy water is a fibrous substance containing a hydrophilic cross-linked polymer in at least the outer layer thereof. As well as slimming on the surface.

The superabsorbent fiber is preferably a core inner layer formed of an acrylic fiber and a superabsorbent polymer as a hydrophilic cross-linked polymer disposed so as to surround the inner layer. A superabsorbent fiber having a double structure composed of the formed outer layer can be used.

Here, a double layer comprising an inner layer serving as a core formed of the acrylic fiber and an outer layer formed of a superabsorbent polymer as a hydrophilic cross-linked polymer disposed so as to surround the inner layer. As the superabsorbent fiber having the structure, for example, a superabsorbent fiber (water swellable fiber) described in Japanese Patent Publication No. 58-10508 can be used. Spinning Co., Ltd.)
Etc. can be used. That is, this water-swellable fiber has a function as a fiber of the acrylic fiber serving as a core,
It is a composite functional fiber having both functions as a superabsorbent polymer of the outer layer.

According to the method for preventing sludge loss according to the present invention, the muddy water supplied into the slot during or after excavation contains highly absorbent fibers.
During the excavation work of the pit, when it encounters the gravel ground, the gravel ground, or other ground with large gaps, there is a possibility that sludge will be lost. The fibers flow into the gaps in the ground due to the pressure of muddy water, etc., and the lubricating action of the slime generated on the surface of the superabsorbent fibers allows the fibers to penetrate the gaps and reach a wide area deep into the surrounding ground. By swelling while clinging to the surrounding soil particles, the gaps are clogged and the flow path of the muddy water is blocked in a wide range, thereby making it possible to effectively prevent lost mud for a long time.

The method for preventing muddy water loss according to the present invention can mix highly water-absorbing fibers in advance when forming muddy water and supply the muddy water mixed with the highly water-absorbing fibers to the slot. In this way, if the highly water-absorbing fiber is mixed into the muddy water during mud making, it becomes easy to uniformly disperse the highly water-absorbing fiber in the muddy water, and even when the soil that easily generates mud is encountered, Without particularly interrupting the flow of the normal excavation work process, it is possible to easily take measures against the lost sludge.

Further, in the method for preventing lost mud according to the present invention, when encountering a ground such as a gravel layer which is likely to cause lost mud, the muddy water near the ground in the ditch is provided with high water absorption through various pipes. It is also possible to feed the fibers together with, for example, pressure water and mix them. According to such a method, it is possible to efficiently prevent sludge loss while reducing the amount of superabsorbent fibers used.

Still further, the method for preventing sludge loss according to the present invention comprises:
When encountering a ground such as a gravel layer that is likely to generate sludge, it is preferable to feed the superabsorbent fibers together with the electrolyte into the mud near the ground in the slot and mix them with the mud. If the superabsorbent fiber is mixed with the electrolyte, the action of the electrolyte can suppress the swelling of the superabsorbent fiber due to water absorption until the electrolyte is washed away by groundwater or the like.Thus, the concentration of the electrolyte is adjusted. By adjusting the gel time of the superabsorbent fiber, the range in which the superabsorbent fiber as the sludge preventing material spreads in the ground can be easily adjusted. In addition, as the electrolyte, for example, potassium hydroxide, sodium hydroxide, sodium chloride, sodium sulfate, and the like can be used, but it is preferable to use sodium chloride, that is, sodium chloride, which is easily available and inexpensive. .

[0023]

EXAMPLES Hereinafter, experimental examples performed to confirm the effects of the method for preventing muddy water in the muddy water method of the present invention will be described. However, the present invention is not limited to such an embodiment.

Experimental Example: A cylindrical transparent container 10 having a diameter of about 20 cm and a height of about 100 cm as shown in FIG. 1 is prepared, and the height of the lower part thereof is about 1/3. Glass balls 14 as spherical bodies were filled. On the other hand, 1000 ml of bentonite muddy water, polymer muddy water and self-hardening stabilizer (SG) were prepared as muddy water, and a separately prepared run ace as a superabsorbent fiber previously immersed in a saline solution was mixed with these muddy waters. , Agitated by hand, dispersed in muddy water, mixed with experimental bentonite muddy water, polymer muddy water, and self-hardening stabilizer (SG)
And The run ace was used as short fibers of about 3 mm, and was mixed into each muddy water at an addition amount of 5 g / l.
Further, the run-ace short fibers could be smoothly dispersed and mixed in each muddy water.

Then, each mud 13 mixed with run ace
Is supplied to the inside of the transparent container 10 from the upper end opening of the transparent container 10, and the water pressure causes the layer of the glass balls 14 filled in the lower part of the container 10 to penetrate, and the muddy water 13 that has penetrated the lower end of the container 10. The glass ball 14 is discharged from a discharge port 11 provided in the
The layer was clogged.

FIG. 2 shows the experimental results. According to these experimental results, the amount of collected mud is less than half of the amount of supplied mud (1000 ml) in any mud. It turned out that an effect was obtained. Moreover, from the observation result of the layer of the glass ball 14 through the transparent container 10,
It was confirmed that the run ace clogged the gap between the glass balls over a wide range by swelling by invading the gap between the glass balls 14 over a wide area without remaining at the surface layer portion of the layer of the glass balls 14. .

Therefore, from the results of the experiment, as shown in FIG. 3, for example, even when the ground 20 is encountered during the excavation work of the slot 20 and sludge is generated through the ground 21, The muddy water 22 located in the vicinity of the gravel ground 21 among the muddy water 22 filled in the hole 20 is supplied with a pumping pipe 23.
If the salt solution in which the run ace is immersed is fed through and mixed, the run ace is
It is presumed that the effect of the present invention is effectively and for a long period of time extended by spreading and swelling the gap of the gravel ground 21 over a wide range and clogging the gravel ground 21 over a wide range.

[0028]

As described in detail above, according to the muddy water prevention method in the muddy water method according to the present application, muddy water as a stable liquid supplied and filled into a slot is lost to the surrounding ground. As a material to prevent sludge mixed in to prevent
Since the water-swellable fiber is used as the highly water-absorbent fiber, the highly water-absorbent fiber spreads widely to the surrounding ground while penetrating gaps in the ground, due to the lubricating effect of the slime generated on its surface, By swelling while clinging to the surrounding soil particles and blocking the muddy water flow path by clogging the gap over a wide range, the effect of preventing muddy water can be enhanced and the effect can be easily maintained for a long period of time.

[0029]

[0030]

In the case of encountering a ground such as a gravel layer which is likely to generate sludge, the superabsorbent fiber is fed together with the electrolyte into the mud near the ground in the groove, and these are mixed into the mud.
So , by the action of the electrolyte whose concentration etc. was adjusted,
The range in which the highly water-absorbing fiber as the sludge preventing material spreads in the ground can be easily adjusted.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of an experiment conducted to confirm the operation and effect of the lost-fluid prevention method according to the present invention.

FIG. 2 is a chart showing experimental results.

FIG. 3 is an explanatory diagram illustrating an embodiment of a lost-slud prevention method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Transparent container 11 Outlet 12 Recovery container 13 Mud 14 Glass ball 20 Slot 21 Gravel ground 22 Mud 23 Pumping pipe

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) E21B 21/00 E02D 15/00

Claims (1)

(57) [Claims] When excavating a pit in the ground to construct an underground structure such as an underground continuous wall or a cast-in-place pile, muddy water is supplied and filled into the pit, and this is used as a stabilizing liquid for the pit. In the muddy water method that excavates while preventing the collapse of the hole wall, it is a muddy water prevention method for preventing the supplied muddy water from escaping to the ground around the slot, and includes a gravel layer, etc. A muddy water method comprising feeding water-swellable fibers as superabsorbent fibers together with an electrolyte to muddy water near the ground in a groove, and mixing the same with muddy water that is likely to cause sludge. Lost mud prevention method.